ABSTRACT
A closer investigation of the radioactive bodies will probably lead to the separation of a number of radioactive products, present in a small proportion among the main products. Thorium produces from itself an intensely radioactive substance, ThX, which can be separated from the thorium in consequence of its solubility in ammonia. It gives rise to a gaseous product, the thorium emanation, and also to another substance which is deposited on the surface of bodies in neighbourhood of the thorium, where it gives rise to the phenomenon known as excited activity. The nomenclature to be applied to the numerous radioactive products is a question of great importance and also one of considerable difficulty. The name emanation was originally given to the radioactive gas from thorium, and has since been applied to the similar gaseous products of radium and actinium. There is every reason to believe that the radio-elements themselves must be regarded as radioactive products of very slow rate of change.
